The principal objective of the Histopathology/Cell Biology Laboratory (Core D) is to provide the participating SCOR investigators with the technical support and expertise necessary for the histological (routine light and electron microscopy), immunohistological and molecular-histological evaluation of biological materials. Fulfillment of this objective will ultimately contribute to an increased understanding of the growth and repair mechanisms of the lung. As in the previous SCOR proposals, the Histopathology Laboratory (Core D) will provide the technical support necessary for the preparation of tissues and cells for examination by both light and transmission and scanning electron microscopy. To this end, expert technical assistance regarding both routine and special stains will be made available to investigators as needed. The immunohistochemistry laboratory has accumulated a large experience in the field of immunohistochemical technologies on both the light and electron microscopic levels. These services will also continue to be provided as needed. The Core D will continue to provide publication- quality photomicrographs and slides for presentation. The addition of a Cell Biology Laboratory to the current SCOR proposal will provide additional areas of expertise available to participating investigators. This laboratory will support the growing need for cell culture facilities and technical support. A cell and tissue culture facility equipped with a laminar air flow hood and CO2 incubators will be made available to participating investigators. In addition, provisions will be available to prepare and store tissue culture media. Finally, liquid nitrogen cell storage tanks will be available to store cells and a registry will be maintained to monitor stored cells. The Cell Biology Laboratory, in collaboration with the Histopathology Laboratory, will provide a centralized facility in which in situ hybridization will be done. In situ hybridization studies utilizing radiolabelled cRNA transcripts will provide investigators with a means by which questions pertaining to gene expression can be examined within the structural framework of a histological section. Since the previous proposal, this technology has been established as a routine research tool in our laboratory.